1. Field of the Invention
This invention relates to the handling of dough for baking, and more particularly concerns a method and apparatus for dispensing successive pieces of dough of constant weight.
2. Description of the Prior Art
Methods and apparatus for advancing, homogenizing and dividing dough into pieces of predetermined uniform weight for baking into bread loaves, buns, rolls and the like are disclosed in U.S. Pat. Nos. 4,960,601; 4,517,212; 4,449,908; 4,424,236; 4,332,538; 4,948,611; and 5,046,940. In general, such apparatus may include a hopper which receives dough, auger means for advancing the dough, metering means which control the advance of the dough, multiple nozzles which receive the metered dough, and cutting means which sever the continuously advancing dough into discrete pieces that fall onto an underlying moving belt. A homogenizing step is usually included, which may be accomplished by mixing means usually referred to as a "developer."
It is important that each dough piece be as equal in weight to each other as possible. The uniformity of weight not only produces products of uniform quality but facilitates the automated handling and packaging of the baked products. Also, the weight of the dough is the most expensive cost factor in manufacturing baked goods, and control of the weight tolerances can reduce the need for excess dough. The production of dough pieces of uniform weight is known as "scaling" in the trade. In general, less than 2% deviation in weight is sought relative to a target weight.
Although various types of metering means, such as rollers, pistons and positive displacement pumps have been employed to achieve improved scaling, inconsistencies are still experienced. One reason for the inconsistencies is that, whereas the metering means advances dough on a constant volume basis, gas-formation produced by the yeast content of the dough can produce non-uniform dough density. Because of the paste-like nature of the dough and the fact that its high moisture content is held in microscopically small rupturable pockets, any variation in pressure or dough flow pattern while advancing through the apparatus can lead to product degradation and scaling inconsistencies. Such factors are particularly evident in systems wherein a single metering means supplies dough to a manifold that supplies a number of parallel extrusion conduits, each terminating in an outlet nozzle.
Various expedients have earlier been explored to remediate flow rate inconsistencies experienced in parallel extrusion conduits that handle dough or other paste-like alimentary product. For example, U.S. Pat. No. 2,679,216 to Grondona discloses a multi-apertured die plate having threaded plugs adapted to adjustably occlude each aperture in order to minimize inter-aperture variations in the extrusion of macaroni paste, said variations being otherwise attributable to variations in the temperature, composition, frictional effects and flow path.
U.S. Pat. No. 4,395,427 to Fischer, et. al., concerns apparatus for advancing baking dough through a plurality of parallel nozzles to deposit shaped pieces of dough onto a moving conveyor leading toward a baking oven. Each nozzle is equipped with adjustable restrictor means for the purpose of equalizing the flow emergent from the several nozzles. The restrictor means is a sphincter-type mechanism involving a pair of opposed plates having facing edges adapted to approach each other in coplanar disposition. The shape of the facing edges is complimentary to the shape of the downstream extrusion orifice, the two shapes acting in concert to produce dough pieces of predetermined shape. Although possibly effective in achieving flow control, the use of slidably interactive plates creates upstream shoulders or stagnant zones wherein dough can accumulate and deteriorate. The plates also disturb the desired laminar flow of the dough. The narrow housings which accommodate the plates in their transverse motion relative to the flow of the dough are prone to fouling with accumulated dough, and are difficult to clean.
U.S. Pat. Nos. 4,948,611 and 5,046,940 to Cummins disclose apparatus for dividing bakery dough into a plurality of streams in separate horizontal conduits, and fine tuning the flow rate of the individual streams by adjustable restrictor means in the form of weir type diaphragm values. The diaphragm/weir combination requires that the flow of dough be asymmetrically diverted toward one side of the conduit and expanded laterally within the valve beyond the normal diameter of the conduit. Such disruption of the flow pattern of the dough, especially in a region close to the extrusion orifice, is detrimental to the quality of the extruded dough.
U.S. Pat. No. 5,350,290 to Honings discloses apparatus similar to the aforesaid Cummins patents but employs adjustable restrictor means in the form of a flexible conduit tube whose cross-sectional area is adjustably diminished by a squeeze bar. Although the Honings conduits are intended to maintain a laminar flow pattern, the action of the squeeze bar is to divert the flow pattern to one side of the conduit and broaden the width of the flow pattern in a manner similar to the aforesaid weir values. Neither the Honings or earlier teachings disclose means for achieving automatic control or buffering of dough flow.
It is accordingly an object of the present invention to provide apparatus for controlling the flow of dough through multiple parallel conduits fed by a single manifold.
It is a further object of this invention to provide apparatus as in the foregoing object which facilitates individualized adjustment of dough flow in each conduit.
It is another object of the present invention to provide apparatus of the aforesaid nature which preserves the laminar flow pattern of the dough through the conduit.
It is a still further object of this invention to provide apparatus of the aforesaid nature which preserves the symmetry of flow with respect to the center axis of the conduit.
It is yet another object of the present invention to provide apparatus of the aforesaid nature which is amenable to easy clean-out.
It is an additional object of this invention to provide apparatus of the aforesaid nature capable of automatically adjusting or buffering flow in a given conduit.
These objects and other objects and advantages of the invention will be apparent from the following description.